Brake diagnosis apparatus for self-propelled vehicle

ABSTRACT

A brake diagnosis apparatus for a self-propelled vehicle can secure the safety of the brake and the productivity of mining and quarrying and can detect widely applicable data including the history. In order to achieve this, there is provided oil temperature detecting means (23) for detecting a cooling oil temperature d immediately after the oil cools a brake; holding time calculating means, for receiving the cooling oil temperature d from the oil temperature detecting means and for calculating a holding time t thereof; and a first adding means (31a), having stored therein a first matrix A, which is sectioned in vertical and horizontal directions at every predetermined cooling oil temperature area and at every predetermined holding time area, for receiving the cooling oil temperature d from any one of the oil temperature detecting means and the holding time calculating means, for receiving the holding time t from the holding time calculating means, for adding a frequency of occurrence value An to the area of the first matrix A which includes the cooling oil temperature d and the holding time t, and for freely outputting the added value to an outer portion.

TECHNICAL FIELD OF THE INVENTION

The present invention relates to a brake diagnosis apparatus for aself-propelled vehicle having a hydraulic brake and a friction platetype hydraulic brake, wherein a movable friction plate attaches to anddetaches from a fixed friction plate responsive to an oil pressure so asto obtain a brake force.

BACKGROUND OF THE INVENTION

As a conventional brake diagnosis apparatus for a self-propelledvehicle, there is a structure, for example, as described in JapaneseUnexamined Patent Publication No. 61115739, for detecting thetemperature which is generated by a brake shoe in a vehicle, forgenerating an alarm at a high temperature, and for controlling atraveling speed. That is, an operator receives the alarm and controlsthe vehicle speed, whereby a poor brake operation can be avoided.

In this case, since a traveling road, for example, in a mine for mining,quarrying, and the like, is not paved, and the vehicle for loading andcarrying material frequently goes down a slope in a continuous manner, abrake is severely used. In this state, when using the apparatus, thealarm and the speed limitation are frequently performed, so that it ishard to increase the productivity of mining and quarrying althoughsafety can be secured. Further, since the data are detected in a pinpoint manner at each current time, it is hard to obtain the brakeperformance of a vehicle as a history.

Accordingly, any application of the detected data by the apparatus islimited to a narrow range.

SUMMARY OF THE INVENTION

The present invention is made by taking the conventional problems intoconsideration, and an object of the present invention is to provide abrake diagnosis apparatus for a self-propelled vehicle which can detectbrake data, including a history, and which can be widely applicable aswell as improving the safety of the brake and the productivity of miningand quarrying.

In accordance with a first aspect of the present invention, there isprovided a brake diagnosis apparatus for a self-propelled vehicle havinga hydraulic brake comprising:

oil temperature detecting means for detecting a cooling oil temperatured immediately after the oil is used for cooling the brake;

holding time calculating means, for receiving the cooling oiltemperature d from the oil temperature detecting means and forcalculating a holding time t of the cooling oil temperature d; and

a first adding means, having stored therein a first matrix A which issectioned in vertical and horizontal directions at every predeterminedcooling oil temperature area and at every predetermined holding timearea, for receiving the cooling oil temperature d from any one of theoil temperature detecting means, for receiving the holding time t fromthe holding time calculating means, for adding a frequency of occurrencevalue An to the section of the first matrix A which includes thedetected cooling oil temperature d and the calculated holding time t atthe respective detecting time, and for freely outputting the addedfrequency of occurrence value to an outer portion.

In accordance with the structure mentioned above, since the detection ofthe brake data is not performed in a pin point manner, in the form ofdetection at each current point in time in accordance with theconventional art, but is based on the frequency of occurrence An, thatis, the use history of the brake, the applicable range of the brake datais widened. That is, a concentration in an abnormal section and anabnormal tendency can be visually recognized in accordance with themagnitude of the frequency of occurrence An of each of the sections inthe first matrix A. Whether or not the heat balance of the total vehicleis good can be judged; and various kinds of countermeasures can betaken, e.g., a clogging of the radiator can be eliminated, a shroud canbe provided in the radiator, a capacity of an oil cooler and theradiator can be increased, a cooling oil amount can be increased, anincline of a downward slope can be changed, a transmission level of atransmission used in the downward slope can be decreased, a drivinghabit of an operator can be improved, and the like. Further, forexample, a trouble in a cooling system can be recognized, and a futuremaintenance plan can be accurately made. Still further, even in theself-propelled vehicle which travels on a non-paved road in a mine andthe like for mining and quarrying, in addition to the effects mentionedabove, it is possible to set an alarm and a speed limit based on thepast, the present and a forecast of the future. Accordingly, the safetyof the brake and the productivity of mining and quarrying can besecured.

In accordance with a second aspect of the present invention, there isprovided a brake diagnosis apparatus for a self-propelled vehicle asstated in the first aspect, wherein the first matrix A has apredetermined area section which is identifiable separately from theother sections. As mentioned above, since a judgment as to whether ornot the heat balance is good is not performed after outputting the firstmatrix A, but is previously stored with the first matrix A, they can berecognized at the same time of outputting the first matrix A.

Further, in accordance with a third aspect of the present invention,there is provided a brake diagnosis apparatus for a self-propelledvehicle having a friction plate type hydraulic brake wherein a movablefriction plate attaches to and detaches from a fixed friction plateresponsive to an oil pressure so as to obtain a brake force, comprising:

oil pressure detecting means, for detecting an oil pressure P;

speed detecting means, for detecting a value corresponding to arotational speed V of the movable friction plate; and

a second adding means, having stored therein a second matrix B which issectioned in vertical and horizontal directions at every predeterminedoil pressure area and at every predetermined rotational speed area, forreceiving the oil pressure P from the oil pressure detecting means, forreceiving the rotational speed V from the speed detecting means, foradding a frequency of occurrence value Bn to the section of the secondmatrix B which includes the detected oil pressure P and the detectedrotational speed V, and for freely outputting the added frequency ofoccurrence value to an outer portion.

Accordingly, since the detection of the brake data is not performed in apin point manner at each point in time in accordance with theconventional art, but is performed on the basis of the frequency Bn, theapplicable range of the brake data can be widened. Accordingly, amultiplied value (=P·V) between a vertical value (an oil pressure) and ahorizontal value (a rotational speed) in the second matrix B is inproportion to the heat generation of the brake, that is, the abrasion ofthe friction brake, particularly a disc. The multiplied value isascertained with regard to the position of each of the sections in thesecond matrix. Accordingly, when the frequency of occurrence Bn isconcentrated in a section having a great P V value, it indicates thatthe heat generation of the brake, that is, the abrasion of the frictionbrake, is frequent. As a result, in the same manner as with the firstaspect of the present invention, various kinds of countermeasures can betaken, e.g., a clogging of the radiator can be eliminated, a shroud canbe provided in the radiator, a capacity of an oil cooler and theradiator can be increased, a cooling oil amount can be increased, anincline of a downward slope can be changed, a transmission level of atransmission used in the downward slope can be decreased, a drivinghabit of an operator can be improved, and the like. Further, it ispossible to prepare a friction plate for replacement, and to make amaintenance plan.

In accordance with a fourth aspect of the present invention, there isprovided a brake diagnosis apparatus for a self-propelled vehicle asstated in the third aspect, wherein the second matrix B has apredetermined area section which is identifiable separately from theother sections. Accordingly, since a judgment of the abrasion amount inthe friction brake and the like is not performed after outputting thesecond matrix B, but is previously stored with the second matrix B, theycan be ascertained at the same time of outputting the second matrix B.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a control block diagram of a brake diagnosis apparatus for aself-propelled vehicle in accordance with an embodiment of the presentinvention; and

FIG. 2 is a schematic view of first and second matrixes displayed on thedisplay device in FIG. 1.

BEST MODE FOR CARRYING OUT THE INVENTION

A brake diagnosis apparatus for a self-propelled vehicle in accordancewith an embodiment of the present invention will be described in detailwith reference to FIGS. 1 and 2.

A self-propelled vehicle of this embodiment is a largesized dump truckfor a mine (hereinafter, referred to as a dump truck), and in FIG. 1, aright side portion of a full-floating axle 2, suspended by a suspensioncylinder 1, is shown.

An axle housing 3 contains a drive shaft 5 therewithin; the left end ofthe drive shaft 5 is engaged with a differential gear (not shown), andthe right end thereof is engaged with the sun gear 6 of the planetarygear apparatus 4, corresponding to a final reduction gear. The rotationof the drive shaft 5 freely rotates the carrier 9 via the planetary gear8, which is provided between the sun gear 6 and the ring gear 7, whichis fixed to and provided on an inner peripheral surface of the right endof the axle housing 3. For example, a rear wheel 10 is fixed to andprovided at the right end of the carrier 9. The dump truck travelsforwardly and backwardly in accordance which a rotational force from thedifferential gear which rotates the rear wheel 10 via the drive shaft 5,the sun gear 6, and the carrier 9.

The carrier 9 is provided with a spline 11, which extends in a lateralhorizontal direction on an outer periphery close to a center of thevehicle body; and the inner teeth of a plurality of discs 12 (movablefriction plates) are meshed with the spline 11. On the other hand, theaxle housing 3 is provided with a spline 13, which extends in a lateralhorizontal direction on an inner periphery close to the center of thevehicle body; and the outer teeth of a plurality of plates 14 (fixedfrictional plates) are meshed with the spline 13 so as to alternatelyplace them with respect to the discs 12 (hereinafter, a combination ofthe discs 12 and the plates 14 will be referred to as a friction brake15). Further, an annular cylindrical 17 member, inwardly fitting annularpiston 16 which is freely brought into contact with the left sidesurface of the plate 14 closest to the center of the vehicle body, isprovided in the axle housing 3.

The dump truck is provided with a rotation type hand lever 18, which isprovided near a steering wheel adjacent to a driver's seat in such amanner as to freely fix a rotation angle, and a foot pedal 19, which isprovided on the floor adjacent to the driver's seat in such a manner asto be freely depressed. In the case of the rotation type hand lever 18,the operator stops the vehicle by rotating the lever 18 a predeterminedangle; and in the case of the foot pedal 19, the operator stops thevehicle by depressing the foot pedal 19 a predetermined amount.Accordingly, an oil pressure P, having a value corresponding to therotation angle or the depressing amount, is generated; the pressurizedoil, having the pressure P flows into the annular cylinder 17 so as tomove the annular piston 16 rightwardly, and a pressing force (a brakeforce) corresponding to the oil pressure P is generated in the frictionbrake 15. That is, the dump truck corresponds to "a self-propelledvehicle having a friction plate type hydraulic brake 15 wherein themovable friction plate 12 engages with or disengages from the fixedfriction plate 14 due to the oil pressure P so as to obtain a brakeforce".

In the structure mentioned above, when the brake is operated, the brakeforce becomes frictional heat in the friction brake 15. In order toradiate the frictional heat, a cooling oil Q is supplied to the frictionbrake 15. That is, the cooling oil Q flows from a cooling hydraulic pump20 into an inlet provided in the axle housing 3, and is injected intothe friction brake 15, via an injection port which is provided in thespline 11 of the carrier 9, to cool the friction brake 15. The coolingoil Q, now having a higher temperature, flows from an outlet provided inthe spline 13 of the axle housing 3 to an oil cooler 21, which isdisposed in an outer portion, is cooled therein and then is stored in atank 22. The cooling oil Q within the tank 22 is again supplied to thefriction brake 15 by the cooling hydraulic pump 20.

Further, in the case wherein the dump truck continuously brakes in acontinuous down slope, it is necessary to rotate the cooling hydraulicpump 20 at a high speed to supply a large amount of cooling oil Q to thefriction brake 15. Accordingly, the operator pulls the rotation typehand lever 18 (a retard lever), and sets the rotational speed of thetransmission to a higher level when entering a certain position, therebyalways using the engine at a high rotational speed. That is, the dumptruck also corresponds to "a self-propelled vehicle having an oil cooledtype brake".

The dump truck is provided with an oil temperature sensor 23 (oiltemperature detecting means), in the middle of the oil passage of thecooling oil Q flowing out from the friction brake 15, for detecting thetemperature d of the cooling oil immediately after being used forcooling the brake. Further, an oil pressure sensor 24 (oil pressuredetecting means) is provided in the oil passage from the rotation typehand lever 18 and the foot pedal 19 to the annular cylinder 17. Stillfurther, a rotational speed sensor 25 (speed detecting means fordetecting a value corresponding to the rotational speed of the discs12), for detecting the rotational speed V of the rear wheel 10, isprovided between the carrier 9 and the rear wheel 10. In this case, therotational speed sensor 25 can be a vehicle speed sensor for detectingthe vehicle speed v and can be provided in the vehicle body. The oiltemperature sensor 23, the oil pressure sensor 24, and the rotationalspeed sensor 25 are connected to a controller 26, and each of thecooling oil temperature d, detected by the oil temperature sensor 23,the oil pressure P, detected by the oil pressure sensor 24, and therotational speed V, detected by the rotational speed sensor 25, isinputted to the controller 26.

The controller 26 has stored in a ROM 28 a first matrix A, which issectioned in vertical and horizontal directions at every predeterminedcooling oil temperature area and at every predetermined holding timearea, and a second matrix B, which is sectioned in vertical andhorizontal directions at every predetermined oil pressure area and atevery predetermined rotational speed area, as shown in FIG. 2. Further,the controller 26 includes a clock pulse oscillator 29, for oscillatinga clock pulse K1 at every predetermined time t₀ (for example, t₀ =1minute); a trigger signal oscillator 30, for receiving the clock pulseK1 from the clock pulse oscillator 29 and for oscillating a triggersignal K2 on the basis of at least one of the signals at a time ofinitiating the clock pulse K1 and at a time of terminating the clockpulse K1; a calculating portion 31 (CPU); and a RAM 32.

The calculating portion 31 stores any one or both of the following twoprograms in the RAM 32, and performs the following processes on thebasis of the programs.

The first program is as follows. When the cooling oil temperature d(=d1), which is detected by the oil temperature sensor 23, is inputted,first adding means 31a within the calculating portion 31 initiallyselects a cooling oil temperature area, which includes the cooling oiltemperature d1, from among the first matrix A. At the same time, itstarts counting the trigger signal K2 from the trigger signal oscillator30 (that is, addition is performed). The addition is continuouslyperformed until the successively inputted cooling oil temperature dbecomes the cooling oil temperature d (=d2) which is included in anothercooling oil temperature area. When the cooling oil temperature becomesd2, the first adding means 31a selects a holding time area, whichincludes the holding time t (=n·t₀), at the cooling oil temperature d1from among the first matrix A, and stores the frequency of occurrence An(=1) in that holding time area in the RAM 32. With respect to thecooling oil temperature d2, the same operation as that of the coolingoil temperature d1 is repeated, so that the contents of the first matrixA within the RAM 32 is renewed.

Thereafter, when the cooling oil temperature area which includes thedetected cooling oil temperature d (=d1) is the same as the cooling oiltemperature area mentioned above, and the holding time area whichincludes the holding time t (=n·t₀) is the same as the holding time areamentioned above, the frequency of occurrence An (=1) is further added tothe frequency of occurrence An (=1) for storage as mentioned above so asto obtain a frequency of occurrence An (=2), whereby the contents of thefirst matrix A within the RAM 32 are renewed. Thereafter, the renewaloperation mentioned above is repeated.

In this case, the holding time calculating means is constituted byincluding the clock pulse oscillator 29, the trigger signal oscillator30, and the calculating portion 31. Further, the cooling oil temperatured1, which is inputted to the first adding means 31a, can be a value suchthat the cooling oil temperature d, as detected by the oil temperaturesensor 23, passes through the holding time calculating means. This isbecause in the holding time calculating means, the cooling oiltemperature d1 is inputted by setting the input time of the firstcooling oil temperature d or the changing time of a subsequent coolingoil temperature d (a changing point between the areas) to be acalculation starting time for the calculation of the holding time.

The second program is as follows. A second adding means 31b within thecalculating portion 31 receives the oil pressure P from the oil pressuresensor 24 and the rotational speed V from the rotational speed sensor25, and selects the oil pressure area which includes the oil pressure Pfrom the second matrix B. Next, it selects the rotational speed areawhich includes the rotational speed V among the selected oil pressurearea from the second matrix B, and stores the frequency of occurrence Bn(=1) in that rotational speed area in the RAM 32.

This procedure can be structured so as to initially select the rotatingspeed area, which includes the rotating speed V from the second matrixB, and then select the oil pressure area which includes the oil pressureP among the selected rotating speed area from the second matrix B, andto store the frequency of occurrence value Bn (=1) in that oil pressurearea in the RAM 32. Since thereafter the procedures are the same asthose of the first program, an explanation thereof will be omitted.

In accordance with the first and second programs, as the dump truck isoperated, the frequency of occurrence values An and Bn are respectivelyadded to the vertical and horizontal sections in the first matrix A andthe second matrix B so as to be stored in the RAM 32. Each of thefrequency of occurrence values An and Bn expresses a history, forexample, expresses a tendency of a travel road condition such as anunevenness, a curve, a down slope, a crossing, a railroad crossing, andthe like, or a habit of the operator, a vehicle condition, and the like.

The first adding means 31a and the second adding means 31b within thecalculating portion 31 can display the first matrix A and the secondmatrix B stored in the RAM 32 as well as each of the frequency ofoccurrence values An and Bn at a predetermined interval or continuouslyon a display device 27. Further, the structure can be made such that acommand sending button (not shown) to the calculating portion 31 isindependently provided, and the matrixes A and B are suitably displayedon the display device 27 in accordance with the operator pushing thecommand sending button. Still further, the structure can be made suchthat the matrixes A and B are copied to a magnetic card or the like,thereby permitting them to be displayed on a display device (not shown)provided within a building. In addition, in the case wherein amicrocomputer which is provided in the dump truck or within thebuilding, has a program which is different from the program mentionedabove and the other data, the display can include the other data and thelike.

Here, it is desirable that the first matrix A and the second matrix Bidentify a particularly significant area section from among the othersections, as shown in an oblique line area in FIG. 2. The details are asfollows.

For example, in the case wherein the frequency An is frequentlygenerated in the rightwardly descending oblique line areas (the areashaving a high temperature and a long time period) shown in the firstmatrix A, the particularly significant area (the oblique line area) inthe first matrix A indicates a problem with the heat balance of theentire vehicle. In this case, various kinds of countermeasures can betaken, e.g. a clogging of the radiator can be eliminated, a shroud canbe provided in the radiator, a capacity of an oil cooler and theradiator can be increased, a cooling oil amount can be increased, anincline of a downward slope can be changed, a transmission level of atransmission used in the downward slope can be decreased, a drivinghabit of an operator can be improved, and the like.

Further, for example, in the case that the frequency of occurrence An isfrequently generated in the rightwardly ascending oblique line areas(the areas having a super high temperature) shown in the first matrix A,the particularly significant area indicates a trouble in a coolingsystem. In this case, it is planned that the cooling system beimmediately repaired or a period for repair be hastened.

On the other hand, the particularly significant area (the oblique linearea) in the second matrix B indicates the following matter. Amultiplied value (=P·V) between a vertical value (the oil pressure P)and a horizontal value (the rotating speed V) in the second matrix B isin proportion to the heat generation of the brake, that is, the frictionbrake, particularly an abrasion of a disc. In this case, strictly, itshould be "substantially in proportion" since a coefficient of frictionof the friction brake is changed in accordance with its temperature;however, in this case, it can be considered to be "in proportion". Then,the multiplied value need not be realized by an actual multiplication,but can be realized by the position of each of the sections in thesecond matrix B. For example, in the case that the frequency Bn isfrequently generated in the rightwardly ascending oblique line areas(the areas having a high temperature and a high speed rotation) shown inthe second matrix B, the particularly significant area indicates thatthere is a lot of heat generation in the brake, that is, abrasion of thefriction brake, particularly the disc.

As a result, in the same manner as with the particularly significantarea in the first matrix A, for example, various kinds ofcountermeasures can be taken, e.g., a clogging of the radiator can beeliminated, a shroud can be provided in the radiator, a capacity of anoil cooler and the radiator can be increased, a cooling oil amount canbe increased, an incline of a downward slope can be changed, atransmission level of a transmission used in the downward slope can bedecreased, a driving habit of an operator can be improved, and the like.Further, a friction brake for replacement can be prepared, and a repairplan can be made.

In accordance with this embodiment, since the detection of the brakedata is not performed at each position in a pin point manner as in theconventional art, but is performed on the basis of each of the frequencyof occurrence values An and Bn showing the history, the range ofapplying the brake data is widened. Further, even in the self-propelledvehicle traveling on the non-paved road in the mine or the like formining and quarrying, it is possible to set an alarm and a speed limitbased on the past, the present, and a forecast of the future. That is,as well as a safety of the brake, a productivity of mining and quarryingcan be secured.

Here, in this embodiment, in order to detect the cooling oil temperatured, the oil temperature sensor 23, for detecting the cooling oiltemperature d immediately after the oil cools the brake, is provided inthe middle of the passage of the cooling oil Q flowing out from thefriction brake 15; however, the structure can be made such that anotheroil temperature sensor (not shown), for detecting the cooling oiltemperature immediately before the cooling oil enters the brake, isprovided in the middle of the passage of the cooling oil Q flowing intothe friction brake 15, so that the temperature difference between theoil temperature before cooling the brake and the oil temperature aftercooling the brake is detected; the temperature difference can be deemedto be "a cooling oil temperature d" and the first program can beperformed. In this case, the changing history of the brake temperaturecan be accurately recognized; however, a history of the heat balance ofthe entire vehicle can not be recognized. Accordingly, in order to knowthe history of the heat balance, it is sufficient to calculate on thebasis of the cooling oil temperature d only from the oil temperaturesensor 23 and to display the result.

INDUSTRIAL APPLICABILITY

The present invention is useful for a brake diagnosis apparatus for aself-propelled vehicle, such as a dump truck and the like, which cansecure safety of the brake and the productivity of mining and quarrying,and which can detect widely applicable data including the history.

What is claimed is:
 1. A brake diagnosis apparatus for a self-propelledvehicle having a hydraulic brake comprising:oil temperature detectingmeans, for detecting a cooling oil temperature d immediately after thecooling oil is used to cool a brake; holding time calculating means, forreceiving the cooling oil temperature d from the oil temperaturedetecting means and for calculating a holding time t of the cooling oiltemperature d; and an adding means, having stored therein a matrix A,which is sectioned in vertical and horizontal directions at everypredetermined cooling oil temperature area and at every predeterminedholding time area, for receiving the cooling oil temperature d from anyone of said oil temperature detecting means and said holding timecalculating means, for receiving the holding time t from the holdingtime calculating means, for adding a frequency of occurrence value An tothe area of the matrix A which includes the cooling oil temperature dand the holding time t at each time, and for freely outputting the addedvalue to an outer portion.
 2. A brake diagnosis apparatus for aself-propelled vehicle as claimed in claim 1, wherein the matrix A has apredetermined area section which is identifiable separately from theother sections.
 3. A brake diagnosis apparatus for a self-propelledvehicle having a friction plate hydraulic brake wherein a movablefriction plate attaches to and detaches from a fixing friction plateresponsive to an oil pressure so as to obtain a brake force, said brakediagnosis apparatus comprising:oil pressure detecting means, fordetecting an oil pressure P; speed detecting means, for detecting avalue corresponding to a rotational speed V of the movable frictionplate; and adding means, having stored therein a matrix B, which issectioned in vertical and horizontal directions at every predeterminedoil pressure area and at every predetermined rotational speed area, forreceiving the oil pressure P from said oil pressure detecting means, forreceiving the rotational speed V from said speed detecting means, foradding a frequency Bn to the section of the matrix B which includes thedetected oil pressure P and the detected rotational speed V, and forfreely outputting the added value to an outer portion.
 4. A brakediagnosis apparatus for a self-propelled vehicle as claimed in claim 3,wherein the matrix B has a predetermined area section which isidentifiable separately from the other sections.